Extracts of leaves and seeds of Ginkgo biloba have been used for many years, originally in China, and now throughout the world, to exert various physiological effects. The seeds of Ginkgo have been used by the Chinese to treat cancer, respiratory and circulatory problems and impaired hearing; seed extracts have been used to promote sexual desire and enhanced longevity. Extracts obtained from Ginkgo leaves have been used in Western cultures for various therapeutic purposes.
A particular extract from leaves, EGb761 (Tebofortan) has been used in clinical trials. On a wt/wt basis, this extract contains 24% of flavone glycosides and 6% terpenoids. Among conditions treated by this and other Ginkgo extracts are cerebral insufficiency, inadequate blood circulation, and various heart conditions. The extracts have also been used as scavengers for free radicals.
The physiological basis for the use of Ginkgo extracts has been explored in a number of studies on model systems. However, of most relevance to the present invention is a study conducted by Kobayashi, N., et al., published in Yakugaku Zasshi (1993) 113:718-724 wherein the above-referenced extract, EGb761, (prepared by extraction of Ginkgo leaves in 70% ethanol) was shown to stimulate hair growth in CH3 strain mice when applied topically to a shaved dorsal surface. These workers attributed this stimulatory affect on the ability of the extracts to enhance blood flow. Ginkgo extracts were employed in this study based on the postulate that they are known to be effective for chilblains, which is aggravated by poor blood circulation.
A large number of active molecules have been identified in Ginkgo leaves, including, most prominently, flavone glycosides and terpenoids. Among the flavone glycosides identified are kaempferol, quercetin, isorhamnetin, sciadopitysin, ginkgetin, amentoflavone, bilobeten, sequoiaflavone and isoginkgetin. The flavone nucleus may be coupled to sugars, including glucose or rhamnose. In particular, the structure of isoginkgetin has been determined and published. It is shown in FIG. 1. The terpenoids include ginkgolides A, B, and C and bilobalide. Ginkgolides are known to inhibit platelet activating factor, thus ginkgolides may be useful in treating asthma, atherosclerosis and stroke when the immune system is stressed and may help restore motor nerves and can also be used to treat certain parasitic infections.
The affects of individual flavanoids derived from Ginkgo have also been studied. Saponara, R., et al., J. Nat. Prod. (1998) 11:1368-1369 showed that individual Ginkgo flavones inhibit the activity of cAMP phosphodiesterase in rat adipose tissue. They also stimulate skin microcirculation. Dell'Agli, M., et al., Planta Med. (2002) 68:76-79 showed that various Ginkgo flavones stimulated the lipolysis in adiposites in a dose-dependent manner. The individual flavones derived from Ginkgo also stimulated human skin fibroblasts and increased production of collagen and extracellular fibronectin, as described by Kim, S. J., et al., Skin Pharmacol. (1997) 10:200-205. Some of the flavones also suppressed lymphocyte proliferation as described by Lee, S. J., et al., Life Sci. (1995) 6:551-558.
To applicants' knowledge, there is no suggestion that the stimulation of hair growth described by Kobayashi (supra) was attributable to the flavanoid components of Ginkgo. 
U.S. Pat. No. 6,410,512 describes the effect of proteasome inhibitors on hair growth. It appears that inhibition of proteasome activity and/or NF-κB activity results in enhanced hair growth. Applicants are aware of no publication or description in the art that associates Ginkgo flavanoids with proteasome inhibition.